1. Technical Field
The present invention relates to a liquid ejecting head including a piezoelectric element, that causes a change in the pressure in a pressure-generating chamber that communicates with a nozzle opening, and that includes a piezoelectric layer and electrodes configured to apply a voltage to the piezoelectric layer. The invention also relates to a liquid ejecting apparatus including such a liquid ejecting head, and a piezoelectric element.
2. Related Art
A piezoelectric element generally includes a layer of piezoelectric material, for example, a crystallized dielectric material, sandwiched between two electrodes. Such a piezoelectric element is mounted on a liquid ejecting head as an actuator device. One example of a liquid ejecting head is an ink jet recording head, in which a pressure-generating chamber communicates with a nozzle opening that ejects ink droplets. The pressure-generating chamber includes a diaphragm, which is deformed using a piezoelectric element to apply pressure to ink in the pressure-generating chamber, thereby ejecting the ink as ink droplets from the nozzle opening.
A high piezoelectricity is required for piezoelectric materials in the piezoelectric layer. A typical example of a piezoelectric material is lead zirconate titanate (PZT), such as that disclosed in JP-A-2001-223404, the disclosure of which is hereby incorporated by reference.
However, due to environmental issues, piezoelectric materials having reduced amounts of lead are desirable. An example of a lead-free piezoelectric material is bismuth ferrite (BiFeO3), which has a perovskite structure represented by ABO3. However, such materials have low relative dielectric constants ∈r, and thus the amount of strain is lower than desired. This is a problem not only in ink jet recording heads, but also in other liquid ejecting heads that discharge liquids other than ink.